Stanford appeared to limp into its matchup with No. 6 USC on Saturday. And, after another tumultuous August (this time because of off-field drama surrounding head coach Steve Sarkisian's personal life), the Trojans turned in two impressive performances, albeit against modest competition, and the bandwagon was filling up.

And then, once again, the Trojans produced a dismal defensive performance as Cardinal QB Kevin Hogan carved up USC in a 41-31 win.

Maybe the best barometer of how much Stanford cranked things up against USC is this: David Shaw's team entered the game 107th in the nation in third-down conversions at 30 percent -- yet it went 8 for 12 against the Trojans on Saturday night. The victory also marks the fourth time in a row that Stanford won in a game that it entered as a double-digit underdog.

More from FoxSports

For USC, it was a similar story in its short tenure under the embattled Sarkisian, who falls to 11-5 with the Trojans. Three of those losses are against unranked teams, and two of them are double-digit-underdog defeats (one of them to a 17-point underdog Boston College last season). The defense seemed tentative and got picked apart. USC has now allowed at least 37 points in five of its past 12 games against Power 5 opponents.

The loss does NOT knock USC out of playoff consideration. After all, it's only one loss -- and its still September.

But for a coach who needed to get off to a good start to mute a lot of the growing skepticism about whether he can handle this job, this is one of the last things he could afford.

The feeling here is that anything less than a 10-win year would feel like a major disappointment in Trojanland. USC has an experienced QB who is a three-year starter (Cody Kessler), plus superstars Adoree' Jackson and Su'a Cravens. And gone are all the depth issues that stemmed from NCAA sanctions.

The biggest question that lurked entering this season was whether Sarkisian -- a guy who had never gotten close to the top of the Pac-12 North -- could lead the Trojans to consistent efforts.

With this home loss to unranked Stanford, the margin for error just got a lot thinner for Sarkisian.